The 95-year-old former President and anti-apartheid icon has been in hospital for more than two months with a recurring lung infection.

"Former president Nelson Mandela continues to receive treatment in hospital in Pretoria and doctors have indicated to President Jacob Zuma that Mandela is making a slow but steady improvement," a statement from the Presidency said.

"The medical team also reiterated that although his health was improving steadily, Madiba still remained in a critical condition," it added.

Zuma asked South Africans to pray for Mandela's recovery and good health, the statement said. The South African President is technically the only person authorized to give public updates about Mandela's health.